Revenue (Details) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2019 USD ($) company MW	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) company MW	Sep. 30, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 2,926	$ 2,986	$ 8,180	$ 8,313
ARP		25	66	142	190
Other non-customer revenue		12	12	40	48
Total revenues	[1]	2,963	3,064	8,362	8,551
Other Non-Customer Revenue
Disaggregation of Revenue [Line Items]
Late payment charges		9	9
Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,436	1,418	3,840	3,868
Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		975	1,045	2,811	2,939
Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		102	139	325	393
Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		371	341	1,090	996
Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		42	43	114	117
Derivative Revenue | Other Non-Customer Revenue
Disaggregation of Revenue [Line Items]
Total revenues		2	4	7	18
Revenue from late payment charges | Other Non-Customer Revenue
Disaggregation of Revenue [Line Items]
Late payment charges				29	28
Regulated Distribution
Disaggregation of Revenue [Line Items]
Total revenues		2,446	2,499	6,756	6,930
Reduction in revenue		4	27	$ 31	109
Decrease in Rider DMR revenue		$ 31
Number of existing utility operating companies | company		10		10
Megawatts of net demonstrated capacity of competitive segment | MW		3,790		3,790
Utility customer payment period				30 days
Regulated Distribution | Residential
Disaggregation of Revenue [Line Items]
Total revenues		$ 1,538	1,572	$ 4,145	4,290
Regulated Distribution | Commercial
Disaggregation of Revenue [Line Items]
Total revenues		600	628	1,759	1,778
Regulated Distribution | Industrial
Disaggregation of Revenue [Line Items]
Total revenues		286	276	786	792
Regulated Distribution | Other
Disaggregation of Revenue [Line Items]
Total revenues		22	23	66	70
Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues		371	341	1,090	996
Reduction in revenue		4	2	11	4
Regulated Transmission | JCP&L | FERC
Disaggregation of Revenue [Line Items]
Annual revenue requirement				155
Regulated Transmission | ATSI
Disaggregation of Revenue [Line Items]
Total revenues		184	167	542	492
Regulated Transmission | TrAIL
Disaggregation of Revenue [Line Items]
Total revenues		55	60	172	183
Regulated Transmission | MAIT
Disaggregation of Revenue [Line Items]
Total revenues		58	43	157	106
Regulated Transmission | Other
Disaggregation of Revenue [Line Items]
Total revenues		74	71	219	215
Operating Segments
Disaggregation of Revenue [Line Items]
Reduction in revenue			29		113
Operating Segments | Regulated Distribution
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		2,588	2,675	7,185	7,420
ARP		25	66	142	190
Other non-customer revenue		23	25	74	84
Total revenues		2,636	2,766	7,401	7,694
Operating Segments | Regulated Distribution | Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,457	1,440	3,903	3,949
Operating Segments | Regulated Distribution | Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		989	1,059	2,853	2,981
Operating Segments | Regulated Distribution | Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		100	133	316	377
Operating Segments | Regulated Distribution | Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0	0	0
Operating Segments | Regulated Distribution | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		42	43	113	113
Operating Segments | Regulated Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		371	341	1,090	996
ARP		0	0	0	0
Other non-customer revenue		4	5	13	14
Total revenues		375	346	1,103	1,010
Operating Segments | Regulated Transmission | Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0	0	0
Operating Segments | Regulated Transmission | Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0	0	0
Operating Segments | Regulated Transmission | Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0	0	0
Operating Segments | Regulated Transmission | Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		371	341	1,090	996
Operating Segments | Regulated Transmission | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0	0	0
Corporate/Other and Reconciling Adjustments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		(33)	(30)	(95)	(103)
ARP		0	0	0	0
Other non-customer revenue		(15)	(18)	(47)	(50)
Total revenues		(48)	(48)	(142)	(153)
Corporate/Other and Reconciling Adjustments | Distribution services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		(21)	(22)	(63)	(81)
Corporate/Other and Reconciling Adjustments | Retail generation
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		(14)	(14)	(42)	(42)
Corporate/Other and Reconciling Adjustments | Wholesale sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		2	6	9	16
Corporate/Other and Reconciling Adjustments | Transmission
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0	0	0
Corporate/Other and Reconciling Adjustments | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 0	$ 0	$ 1	$ 4

[1] Includes excise and gross receipts tax collections of $100 million and $104 million during the three months ended September 30, 2019 and 2018, respectively, and $283 million and $293 million during the nine months ended September 30, 2019 and 2018, respectively.